关于hibernate的哪些事儿

Posted 2021-03-06 codeleader

hibernate与spring整合

方式一：无障碍整合：带Hibernate配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
    xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd
    http://www.springframework.org/schema/aop
    http://www.springframework.org/schema/aop/spring-aop.xsd
    http://www.springframework.org/schema/tx 
    http://www.springframework.org/schema/tx/spring-tx.xsd">
     
     <!-- Spring整合Hibernate -->
     <!-- 引入Hibernate配置信息===== -->
     <bean id="sessionFactory" class="org.springframework.orm.hibernate5.LocalSessionFactoryBean">
        <!-- 引入Hibernate配置文件 -->
        <property name="configLocation" value="classpath:hibernate.cfg.xml"/>
     </bean>

     
     <!-- 配置事务管理器 -->
     <bean id="transactionManager" class="org.springframework.orm.hibernate5.HibernateTransactionManager">
       <property name="sessionFactory" ref="sessionFactory"/>
     </bean>
     
     <!-- 开启注解事务,在业务层使用注解@Transactional -->
     <tx:annotation-driven transaction-manager="transactionManager"/>
    
     <!--  通过context标签引入jdbc.properties，在Hibernate核心配置文件里，免去 -->
 
     
     <!-- 配置C3P0连接池，在Hibernate核心配置文件里面，免去 -->

    
    <!-- 配置Action -->
    <bean id="customerAction" class="com.ssh.web.action.CustomerAction" scope="prototype">
       <property name="customerService" ref="customerService"/>
    </bean>
    
    <!-- 注入CustomerService -->
    <bean id="customerService" class="com.ssh.service.impl.CustomerServiceImpl">
    <property name="customerDao" ref="customerDao"/>
    </bean>
    
    <!--
     注入Dao 
    CustomerDaoImpl继承HibernateDaoSupport,在Dao注入SessionFactory,创建HibernateTemplate模版
    -->
    <bean id="customerDao" class="com.ssh.dao.impl.CustomerDaoImpl">
    <property name="sessionFactory" ref="sessionFactory"/>
    </bean>
    
    
</beans>

方式二：不带Hibernate核心配置文件，将核心配置文件给Spring管理

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
    xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd
    http://www.springframework.org/schema/aop
    http://www.springframework.org/schema/aop/spring-aop.xsd
    http://www.springframework.org/schema/tx 
    http://www.springframework.org/schema/tx/spring-tx.xsd">
     
     
     <!--通过context标签引入jdbc.properties -->
     <context:property-placeholder location="classpath:jdbc.properties"/>
     
     <!-- 配置C3P0连接池 -->
     <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
       <property name="driverClass" value="${jdbc.driverClass}"/>
       <property name="jdbcUrl" value="${jdbc.url}"/>
       <property name="user" value="${jdbc.user}"/>
       <property name="password" value="${jdbc.password}"/>
     </bean>
     
     <!-- Spring整合Hibernate -->
     <!-- 方式二：不带Hibernate核心文件配置===== -->
     <bean id="sessionFactory" class="org.springframework.orm.hibernate5.LocalSessionFactoryBean">
          <!-- 注入连接池 -->
          <property name="dataSource" ref="dataSource" />
          
          <!-- 配置Hibernate相关属性 -->
          <property name="hibernateProperties">
          
           <props>
           <!-- 配置方言,打印语句,格式化sql,自动建表 -->
              <prop key="hibernate.dialect">org.hibernate.dialect.mysqlDialect</prop>
              <prop key="hibernate.show_sql">true</prop>
              <prop key="hibernate.format_sql">true</prop>
              <prop key="hibernate.hbm2ddl.auto">update</prop>
           </props>
          </property>
          
          <!-- 设置映射 -->
          <property name="mappingResources">
          <list>
             <value>com/ssh/domain/Customer.hbm.xml</value>
          </list>
          
          </property>
          
     </bean>

     
     <!-- 配置事务管理器 -->
     <bean id="transactionManager" class="org.springframework.orm.hibernate5.HibernateTransactionManager">
       <property name="sessionFactory" ref="sessionFactory"/>
     </bean>
     
     <!-- 开启注解事务,在业务层使用注解@Transactional -->
     <tx:annotation-driven transaction-manager="transactionManager"/>
    
    
    <!-- 配置Action -->
    <bean id="customerAction" class="com.ssh.web.action.CustomerAction" scope="prototype">
       <property name="customerService" ref="customerService"/>
    </bean>
    
    <!-- 注入CustomerService -->
    <bean id="customerService" class="com.ssh.service.impl.CustomerServiceImpl">
    <property name="customerDao" ref="customerDao"/>
    </bean>
    
    <!--
     注入Dao 
    CustomerDaoImpl继承HibernateDaoSupport,在Dao注入SessionFactory,创建HibernateTemplate模版
    -->
    <bean id="customerDao" class="com.ssh.dao.impl.CustomerDaoImpl">
    <property name="sessionFactory" ref="sessionFactory"/>
    </bean>
    
    
</beans>

 

<properties>
<property name="hibernate.show_sql" value="true" />      
<property name="hibernate.hbm2ddl.auto" value="create" />
</properties>
结果在测试时，老是发现数据库表数据丢失。这个参数以前没怎么用，查了一圈其它的东东，最后才定位到这个上面。赶紧查了一下Hibernate的参数配置，解释如下：

hibernate.hbm2ddl.auto Automatically validate or export schema DDL to the database when the SessionFactory is created. With create-drop, the database schema will be dropped when the SessionFactory is closed explicitly. eg. validate | update | create | create-drop

其实这个参数的作用主要用于：自动创建|更新|验证数据库表结构。如果不是此方面的需求建议set value="none".

其它几个参数的意思，我解释一下：

validate               加载hibernate时，验证创建数据库表结构
create                  每次加载hibernate，重新创建数据库表结构，这就是导致数据库表数据丢失的原因。
create-drop        加载hibernate时创建，退出是删除表结构
update                 加载hibernate自动更新数据库结构

以上4个属性对同一配置文件下所用有的映射表都起作用